Reset fuse plug



June 16, 1936.

D. s. RIVERS ET AL RESET FUSE PLUG Filed March 11, 1935 Inventors, Durward J Pit/era.

and P095. Storms Wm Attorney a Patented June 16, 1936 a 2 2,044,449

UNITED STATES PATENT OFFICE $344,449 RESET FUSE PLUG Durwar S. Rivers and Roy 8- Storm Indianapolis, Ind.

Application Mnlch 11, 1935, Serial No. 10,468 8 Claims- (CL 200-116) This invention relates to the art of fuse plugs sively draw the plate down against the material and has for one of its primary objects the pro- I and the base Ill.

vision of a structure permitting resetting or re- The wire I1 is then bent around and over the establlshingof the circuit through the plug folupper end of the stud II and carried across subso lowing an interruption of the circuit due to an stantially horizontally to have its end brought 5 overload so that regardless of the number of cirinto contact with the bar it and there welded cult interruptions, the circuit may again be re-' or soldered to form a good electrical contact. established without having to replace any fuse This wire I! is made out of some suitable wire element. which has a high degree of expansion when 10 w A further important object of our invention is heated by flow of a current therethrough so that 10 to provide a structure which will be positive in with the correct diameter and length of wire will operation so that the circuit will. be interrupted cause a longitudinal expansion of that wire I! at the desired overload without danger of failure so as to rock'thebar ll outwardly a slight disof the circuit to open; A still further important tance which is in reality measured in terms of to. object is to provide a structure which may be thousandths of an inch. is readily manufactured and easily assembled at a We form a cylindrical member, hereinafter minimum cost and which will provide for a unitermed a tube It and connect it to the base l0 form load carrying rating such that the device by two prongs l9 and which are frictionally may be manufactured in quantity and still have inserted and engaged in holes 2| extending ver- 20 the desired degree of circuit interruption atthe tically through the base it. The lower end of 20 fixed maximum load. the tube IB is pushed downwardly into contact These and other objects and advantages such with the upper side of, thelbase III. A slot 22 as the novel combination of the various eleis provided in one side of the tube It within ments as set forth in the claims will become which the bar enters so asto permit the free 95 apparent to those versed in the art in the fol rocking thereof. on the opposite side of the lowing description ofthe invention as illustrated tube I8 is provided a vertical recess along which by the accompanying drawing, in which i is placed a conductor 23, here shown as being Fig. 1 is a side elevation of a structure .emin the nature of a flat strap. The upperend of vbodying our invention; the tube I8 is slotted immediately above this 90 Fig, 2, an elevati of the reverse i recess to permit the upper end of the strap 23 Fig. 3. a bottom plan view; to be turned inwardly to enter through the slot Fig, 4, -um mngvem u on the line into the tube l8. The upper end of this strap H m 1 3; 22 thus turned inwardly is at-the same level 1; 5, horizon trmvem section on the as that of the upper end of the bar I! which is m H in 1 also provided with an inturned end. 35 rm 5, a horizontal section on the The lower end of the at p 23 is turned out line H 111 Pm 4, and wardly along the base Ill and thence upwardly Fig. 7, a central vertical section through the to mm The b is further- 0 operating plum vided with a transverse partition or floor 24 spaced a short distance above the wire H. A new interme iates? m a is M m the m M on this floor 24 and a plunger 26 is dropped into We form a base ID to have a central stud II a terminating on the under side of the base by a f rzg z g g ifig a side rest 9 the contact head l2. 0n the upper side of the base g a is provgded to i down over the tube 45 a recess m the nature of slot mm which I! by a more or less cylindrical portion the outer loosely fitted the foot I! of a rocker bar ll. In s lower end of which is threaded to receive a ferthe mm herein shmmpiece of mating rule 28 therearound. This ferrule 28 is i'ormed material I! is placed on the base It to straddle with an intumed annular flange 29 which engages the the n rockably the'under side of the base I! so that when the 50 retain that foot in the base recess. On top of ferrul is drawn. up on the body 11, t e base and v the m r l i Placed a terminal P t body 21 are drawn snugly together. The outer Of a wire H. The plate "and material I fit upturned end; of the strap 23 is carried in 5 over the upper end of the stud H which is spun v slight depression cutting acrom through the. 6' or riveted over onto th plate to c mm-u threads of thebodyl'hbutis maintained in'fric .down into contact with tional engagement with the ferrule to form an electrical connection therewith. Preferably the upper e'dg'e of the ferrule 28 is pushed inwardly into the upper end of the recess within which the outer end of the strap 23 rests so as to prevent unwarranted turning of the ferrule on the body 21. The upper end of thetube i8 preferably engases against the inside upper end of the body 21. A hole is provided in the upper end of the body 2'! through which a shaft 30 may slidably extend from the plunger 26. When the body 21 is drawn the base In by the ferrule 28, the plunger 26 is pulled downwardly to compress the spring 25 thereunder somewhat.

The plunger 26, Fig. 7, is made of some suitable insulating material and has a metallic band 3| therearound located at the upper end thereof. This band 3| has the upper portion thereof relieved slightly to form a shoulder 32 of very slight proportion. In fact it is preferred that the recess be not more than a few thousandths of an inch deep. The shoulder may even be slightly rounded.

In the position as shown in Fig. 4, the fuse is in the open circuit setting. Now by pushing downwardly on the shaft 30, the plunger 26 is pushed downwardly also until the shoulder 32 is carried down sufilciently'to permit the in turned ends of the bar I4 and of the strap 23 to slip over the top of the shoulder whereupon pressure on the shaft 30 may be released so that these ends thus engaging over the shoulder on the plunger will retain the plunger in that lowered position against the upward push of the spring 25. It is to be noted that the normal position of both the bar l4 and of the inturned end of the strap 23 is such as to be in yielding contact with the plunger 26 so that both of the inturned ends of those members spring inwardly when permitted. The plunger 26 fits sufficiently loose within the tube l8 as to permit the ends of these two members to spring over the shoulder on the plunger.

Now when the fuse plug is inserted in the usual panel (not shown) and current is allowed to flow through the fuse following a circuit established through the stud LI, wire l'l, bar M, band 3|, strap 23, and the ferrule 28. When .the flow of this current exceeds the amount for which the wire I! has been designed'as to length and diameter, there will then be a suflicient longitudinal expansion of that wire due to the heat of that predetermined current flow which will cause the bar M to be pushed outwardly thereby releasing its inturned end from over the lected that should for any reason the bar lfiiot be pushed out of contact with the band 3|, continual flow of that overload current will cause the wire to melt and thereby break the circuit.

contacting the plunger, if at While we have herein shown and described our invention in the best form as now known to us, it is obvious that structural changes may be made without departing from the spirit of the invention, and we, therefore, do not desire to be limited to that precise form beyond the limitations as may be imposed by the following claims.

We claim:

1. The combination of a base, a central stud carried by the base, an expansible member electrically connected to the stud, a rocker bar shifted by expansion of said member, a body, a ferrule interconnecting the body and the base, a conductor leading from the ferrule and having an inturned end, an end turned inwardly from said bar opposite said conductor end, a plunger loosely fitted to have lateral play and having a metal member thereon, spring means urging the plunger away from said ends, and a shoulder on the metal member on said plunger engaging said ends to permit them to contact said metal member and releasably hold said plunger against the urging of said spring, whereby shifting of said bar by said expansible member will cause it to move from and release said plunger.

2. The combination of a base, a central stud carried by the base, an expansible memberelectrically connected to the stud, a rocker bar shifted by expansion of said member, a body, a ferrule interconnecting the body and the base, a conductor leading from the ferrule and having an inturned end, an end turned inwardly from said bar opposite said conductor end, a plunger loosely fitted to have lateral play and having a metal member thereon, spring means urging the plunger away from said ends, and a shoulder on the metal member said plunger engaging said ends to permit them to contact said metal member and releasably hold said plunger against the urging of said spring, whereby shifting of said bar by said expansible member will cause it to move from and release said plunger, a tube carried between said base and body,-sald spring being within the tube, and said plunger being slidably carried in the tube.

The combination of a base, a central stud carried by the base, an expansible member electrically connected to the stud, a rocker bar shifted 'turned end, an end turned inwardly from said bar opposite said conductor end, a plunger loosely fitted to have lateral play and having a metal member thereon, spring means urging the plunger away from said ends, and a shoulder on the metal member on said plunger engaging said ends to permit them to contact said metal member and releasably hold said plunger against the urging of said spring, whereby shifting of said bar by said expansible member will cause it to move from and release said plunger, said inturned ends entering said tube through apertures therein to be in the path of the plunger.

4. The combination of a base, a central stud carried by the base, an expansible member electrically'connected to the stud, a rocker bar shifted by expansionof said member, a body, a ferrule interconnecting the body and the base, a conductor leading from the ferrule and having an inturned end, an end turned inwardly from said bar opposite said conductor end, a plunger loosely fitted to have lateral play and having a metal member thereon, spring means urging the plunger away from said ends,v and a shoulder on the member thereon,

on said plunger engaging said metal member ends to permit them to contact said metal member and releasably hold said plunger against the urging of said spring, whereby shifting of said bar by said expansible member will cause it to move from and release said plunger, said inturned ends entering said tube through apertures therein to be in the path of the plunger, and said metal member forming a band around the plunger.

5. The combination of a base, a central stud carried by the base, an expansible member electrically connected to the stud, a rocker bar shifted byexpansion of said member, a body, a ferrule interconnecting the body and the base, a conductor leading from the ferrule and having an inturned end, an end turned inwardly from said bar opposite said conductor end, a plunger loosely fitted to have lateral play and having a metal spring means urging the plunger away from said ends, and a shoulder on said plunger engaging said ends to permit them to contact said metal member and releasably hold said plunger against the urging of said spring, whereby shifting of said bar by said expansible member will cause it to move from and release said plunger, said inturned ends entering said tube through apertures therein to be in the path of the plunger, and said metal member forming a band around the plunger, and said shoulder being formed in slight relief on said band.

6. A resetting plug fuse comprising a base, a central conducting stud through the base, an upwardly extending rocker bar, means rockably retaining the bar on the base, acurrent overload expanding member interconnecting said stud and said bar, an enclosing body, a ferrule fitting over said base and screw-threadedly engaging the body, a conductor engaging the ferrule and extending therefrom in an upwardly direction to have an upper inturned end, an inturned end on said bar opposite said other end, a plunger loosely fitted to have lateral play and having a metallic portion adapted to be passed between said ends to contact therewith, means guiding said plunger toward and away from those ends, spring means normally urging said portion out of contact with said ends, and a shoulder in slight relief on the metal member on the plunger adapted to be engaged by said ends to retain said portion in contact therewith.

'7. A resetting plug fuse comprising a base, a central conducting stud through the base, an upwardly extending rocker bar, means rockably retaining the bar on the base, a current overload expanding member interconnecting said stud and said bar, an enclosing body, a ferrule fitting over said base and screw-threadedly engaging the body, a conductor engaging the ferrule and extending therefrom in an upwardly direction to have an upper inturned end, an inturned end on said bar opposite said other end, a plunger having a metallic portion adapted to be passed'between said ends to contact therewith, means plunger toward and away from those ends, spring means normally urging said portion out of contact with said ends, and a shoulder on the metal member on the plunger adapted to be engaged by said ends to retain said portion in contact therewith, said guiding means comprising a tube into which said ends project, said plunger being loosely fitted in the tube to permit slight lateral move ment for disengagement of the shoulder from said conductor end upon movement thereaway of said bar end.

8. A resetting plug fuse comprising a base, a central conducting stud through the base, an upwardly extending rocker bar, means rockably retaining the bar on the base, a current overload expanding member interconnecting said stud and said bar, an enclosing body, a ferrule fitting over said base and screw-threadedly engaging the body, a conductor engaging the ferrule and extending therefrom in an upwardly direction to have an upper inturned end, an inturned end on said bar opposite said other end, a plunger having a metallic portion adapted to be passed between said ends to contact therewith, means guiding said plunger toward and away from those ends, spring means normally urging said portion out of contact with said ends, and a shoulder on the metal member on the plunger adapted to be engaged by said ends to retain said portion in guiding said contact therewith, said guiding means comprising a tube into which said ends project, said plunger being loosely fitted in the tube to permit slight lateral movement for disengagement of the shoulder from said conductor end upon movement thereaway of said bar end, a partition in said tube, said spring means comprising a compression spring within the tube and bearing between said partition and said plunger.

DURWARD S. RIVER ROY .B. STORMS. 

